1. Field of the Invention
The present invention relates generally to fluid flow monitoring and measurement, and more specifically to a flowmeter apparatus for connection to a preexisting fitting in a fluid circuit such as a filter head, and a method of flow measurement utilizing such an apparatus.
2. Description of Related Art
Pressurized fluid delivery systems find application in a number of fields for a wide variety of purposes. For example, hydraulic power transmission systems transmit power through a pressurized working fluid, typically a petroleum-based or fire-resistant water based or synthetic liquid, within a fluid circuit comprising a fluid conduit such as pipe, tubing, or hose. These systems can be stationary, or can be mobile, such as a vehicle-mounted hydraulic system. Examples of hydraulic power transmission systems include, without limitation: systems for raising and lowering rail wheels on bi-modal (i.e., having rubber tires for road transport and steel wheels for rail transport) vehicles; load lifting power systems on forklifts, earth-moving machinery, and other heavy equipment; brake and steering systems on vehicles including automobiles and trucks; vehicle lifts; and other fluid power systems.
Pressurized fluid delivery systems are also common in a number of other applications, in addition to power transmission systems. For example, lubricating oil in automotive and other types of engines and drive systems is distributed under pressure via a fluid circuit. Likewise, fuel and cooling water systems in engines utilize pressurized fluid delivery circuits. Drinking water and natural gas are also distributed to points of use under pressure through fluid delivery circuits. The working fluid or delivered fluid distributed through a pressurized fluid delivery system can be a liquid or a gas. For example, in addition to liquids such as the above-described hydraulic fluids and oils, pressurized air or other gas is used as the working fluid in pneumatic power systems, and pressurized air or other gas are distributed by breathing air systems and other gas delivery systems.
One feature common to many pressurized fluid circuits is the provision of one or more filtering devices for removal of contaminants from the fluid. For example, hydraulic power systems typically include an inline filter in the return flow line to remove any particulate matter prior to recirculating through the pump. Other examples include oil filters in automotive lubrication systems, charcoal filters in drinking water delivery systems, and HEAP filters in air delivery systems, to name but a few. Because the filter elements of filtering devices must be periodically replaced or cleaned, fluid circuits commonly include a detachable connection point, or "filter head," where the filter element is installed. In most instances, these filter heads are provided in readily accessible locations in the fluid circuit, and valving or other shut-off devices are provided as necessary to prevent or minimize fluid escape upon removal of the filter element.
It has been found desirable, for a number of reasons, to monitor the flow characteristics of fluid flow within a fluid circuit. For example in troubleshooting, maintenance and repair of the fluid circuit and related equipment, it is often helpful to measure the pressure or flowrate of a fluid flow at one or more locations in an existing fluid circuit. Likewise, for quality control purposes, it is often desired to test a new fluid circuit by measuring the pressure or flowrate of a fluid flow at one or more locations in the circuit. A variety of flow monitoring devices have previously been developed, but have been found to be less than fully satisfactory for many applications. For example, previously known inline flowmeters typically require that sections of the fluid circuit be disconnected to permit installation of the flowmeter. Removal of the flowmeter then requires another disconnection of the circuit. This can be time consuming and expensive, and can result in considerable loss of fluid from the circuit. Previously known external flowmeters using ultrasound or other non-invasive means for measuring flowrates in a circuit are often expensive, difficult to operate, less accurate than inline flowmeters, and may be limited to application with certain conduit materials.
Thus it can be seen that a need yet exists for an apparatus capable of monitoring the flow characteristics of a fluid through a fluid circuit, which apparatus can be easily and inexpensively installed, used and removed. A need also exists for a method of monitoring flow characteristics in a fluid circuit using such a device. It is to the provision of an apparatus and method meeting these and other needs that the present invention is primarily directed.